To investigate the potential of bone marrow mononuclear cells (BM-MCs) in the regeneration of hepatic lesions induced by Schistosoma mansoni (S.mansoni) chronic infection.Female mice chronically infected with S.mansoni were treated with BM-MCs obtained from male green fluorescent protein (GFP) transgenic mice by intravenous or intralobular injections. Control mice received injections of saline in similar conditions. Enzyme-linked immunosorbent assay (ELISA) assay for transforming growth factor-beta (TGF-beta), polymerase chain reaction (PCR) for GFP DNA, immunofluorescence and morphometric studies were performed.Transplanted GFP(+) cells migrated to granuloma areas and reduced the percentage of liver fibrosis. The presence of donor-derived cells was confirmed by fluorescence in situ hybridization (FISH) analysis for detection of cells bearing Y chromosome and by PCR analysis for detection of GFP DNA. The levels of TGF-beta, a cytokine associated with fibrosis deposition, in liver fragments of mice submitted to therapy were reduced. The number of oval cells in liver sections of S.mansoni-infected mice increased 3-4 fold after transplantation. A partial recovery in albumin expression, which is decreased upon infection with S.mansoni, was found in livers of infected mice after cellular therapy.In conclusion, transplanted BMCs migrate to and reduce the damage of chronic fibrotic liver lesions caused by S.mansoni